Method for producing polymers having isotactic or syndiotactic regions

ABSTRACT

A process for preparing a polymer having isotactic or syndiotactic regions (ordered regions for short) by polymerizing polymerizable compounds (monomers) in the presence of an optically active compound as complexing agent, wherein more than 50% by weight of the optically active compound is in the form of only one of the possible enantiomers, the polymerization takes place at temperatures below 20° C., and at least 10% by weight of the monomers are prochiral compounds.

The invention relates to a process for preparing polymers havingisotactic or syndiotactic regions (ordered regions for short) bypolymerizing polymerizable compounds (monomers) in the presence of anoptically active compound as complexing agent, wherein

-   -   more than 50% by weight of the optically active compound is in        the form of only one of the possible enantiomers,    -   the polymerization takes place at temperatures below 20° C., and    -   at least 10% by weight of the monomers are prochiral compounds.

The invention also relates to polymers obtainable by this process and tothe use of these polymers.

DE-A-19533269 and U.S. Pat. No. 5,521,266 disclose a process offree-radical polymerization of sparingly water-soluble orwater-insoluble monomers in aqueous systems. That process usescyclodextrin as a complexing agent.

The use of noncyclic polysaccharides as complexing agents is describedin DE-A-19650790.

In a presentation to the Macromolecular Colloquium Professor Dr. Ritter,incumbent of the Chair in Chemistry at the Heinrich Heine University,Düsseldorf, mentioned on Mar. 27, 2003 that the polymerization of methylmethacrylate in the presence of cyclodextrin may be accompanied byincreased formation of fractions of isotactic regions.

Synthetic polymers have diverse uses. Of particular importance is theiruse as binders in coating compositions, e.g., protective coatings ordecorative coatings, or in adhesives, or as binders for consolidatingfiber webs. For utilities of this kind the desire is in particular forbinders having good elasticity.

It is an object of the present invention to provide polymers havingimproved elasticity.

We have found that this object is achieved by the process defined at theoutset and by the polymers obtainable by said process, and by their use.

The polymers prepared by the process of the invention have isotactic orsyndiotactic regions (ordered regions for short). Unordered regions areatactic.

The tacticity describes the stereoisomerism of polymers wherein thecopolymerized monomers possess asymmetric centers which may in sequencehave a strictly consistent configuration (isotactic: R,R,R . . . orS,S,S . . . configuration) or in sequence a strictly alternatingconfiguration (syndiotactic: R,S,R,S . . . ).

The configuration may alternatively switch arbitrarily between R and S(unordered regions).

The isotactic or syndiotactic regions are each composed of only one kindof monomer (homopolymer regions) or of two monomers which polymerize instrict alternation, e.g., maleic acid and diisobutene.

The monomers to be used for the ordered regions must, accordingly, beprochiral; that is, following their polymerization they form asymmetriccenters in the resultant polymer.

In accordance with the invention the polymerization takes place in thepresence of an optically active compound which forms a complex with themonomers to be polymerized.

In the form in which it is used this optically active compound consiststo the extent of more than 50% by weight of only one of the possibleenantiomers of this compound.

Preferably it consists to the extent of more than 70% by weight of onlyone of the enantiomers.

With particular preference the optically active compound is composed100% by weight of only one enantiomer; in other words, it comprisesexclusively a single one of the possible stereoisomeric forms (image ormirror image). At the same time, as a complexing agent, this compoundmust be capable of forming a complex with the monomer to be polymerized.

Preferably, within the complex, the monomer to be polymerized isspatially surrounded by the complexing agent.

Corresponding optically active compounds which are suitable ascomplexing agents are, for example, cyclodextrins (see also W. Saenger,Angew. Chemie Int. Ed. Engl. 1980, 19, 344) or noncyclicpolysaccharides, especially starch degradation products. Suitablecyclodextrins include the cyclodextrins described in the literaturereference given above. They are obtained, for example, by enzymaticdegradation of starch as are composed of from 6 to 9 D-glucose unitslinked to one another by an α-1,4-glycosidic bond. α-Cyclodextrin iscomposed of 6 glucose molecules. Also suitable are compounds whichcomprise cyclodextrin structures. By compounds which comprisecyclodextrin structures are meant reaction products of cyclodextrinswith reactive compounds, e.g., reaction products of cyclodextrins withalkylene oxides such as ethylene oxide, propylene oxide, butylene oxideor styrene oxide, reaction products of cyclodextrins with alkylatingagents, such as C₁ to C₂₂ alkyl halides, e.g., methyl chloride, ethylchloride, butyl chloride, ethyl bromide, butyl bromide, benzyl chloride,lauryl chloride, stearyl chloride or behenyl chloride, and dimethylsulfate. Cyclodextrin can also be modified further by reaction withchloroacetic acid. Cyclodextrin derivatives which comprise cyclodextrinstructures are also obtainable by enzymatic linkage with maltoseoligomers. Examples of reaction products of the type indicated aboveinclude dimethyl-β-cyclodextrin, hydroxypropyl-β-cyclodextrin, andsulfonatopropyl-hydroxypropyl-β-cyclodextrin. Of the compounds of group(a) it is preferred to use α-cyclodextrin, β-cyclodextrin,γ-cyclodextrin and/or 2,6-dimethyl-β-cyclodextrin.

The cyclodextrins are normally present entirely in one of the possibleenantiomeric forms.

The non cyclic polysaccharides include both unmodified polysaccharidesand modified polysaccharides, e.g., polysaccharides which have beenfully or partly derivatized on the OH groups. Polysaccharides of theinvention are soluble in water or at least swellable in water. Thesaccharide is preferably a water-soluble or water-swellable starch or achemically modified starch. The water-soluble or water-swellablestarches comprise, for example, native starches which have been madeswellable or soluble in water by boiling with water, or starchdegradation products obtained from the native starches by hydrolysis, inparticular by acid-catalyzed hydrolysis, enzyme-catalyzed hydrolysis oroxidation. Degradation products of this kind are also referred to asdextrins, roast (or torrefaction) dextrins or saccharified starches.Their preparation from native starches is known to the skilled workerand is described for example in G. Tegge, Stärke und Stärkederivate[Starch and Starch Derivatives], EAS Verlag, Hamburg 1984, p. 173ff andp. 220ff, and also in EP-A 0441 197. Native starches which can be usedare virtually all starches of plant origin, examples being starchesobtained from corn, wheat, potato, tapioca, rice, sago, and commonsorghum.

Preference is also given to chemically modified starches. By chemicallymodified starches are meant those starches or starch degradationproducts in which the OH groups are at least partly in derivatized form,e.g., in etherified or esterified form. Chemical modification can beperformed both on the native starches and on the degradation products.It is also possible to convert chemically modified starches subsequentlyinto their chemical modified degradation products.

The esterification of starch can take place with both organic andinorganic acids, their anhydrides or their chlorides. Common esterifiedstarches are phosphated and/or acetylated starches and starchdegradation products. Etherification of the OH groups can take place,for example, using organic halogen compounds, epoxides or sulfates inaqueous alkaline solution. Examples of suitable ethers are alkyl ethers,hydroxyalkyl ethers, carboxyalkyl ethers, allyl ethers, and cationicallymodified ethers, e.g. (trisalkylammonium)alkyl ethers and(trisalkylammonium)hydroxyalkyl ethers. Depending on the nature of thechemical modification the starches or starch degradation products may beneutral, cationic, anionic or amphiphilic. The preparation of modifiedstarches and starch degradation products is known to the skilled worker(see. Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., Vol. 25,p. 12-21 and literature cited therein).

One preferred embodiment of the present invention uses water-solublestarch degradation products and their chemically modified derivativesobtainable by hydrolysis, oxidation of enzymatic degradation of nativestarches or chemically modified starch derivatives. Starch degradationproducts of this kind are also referred to as saccharified starches (seeG. Tegge, p. 220ff). Saccharified starches and their derivatives areavailable commercially as such (e.g., C*pur products 01909, 01908,01910, 01912, 01915, 01921, 01924, 01932 or 01934 from CerestarDeutschland GmbH, Krefeld) or can be prepared by degrading standardcommercial starches using known methods, for example, by oxidativehydrolysis with peroxides or enzymatic hydrolysis, starting from thestarches or chemically modified starches. Particular preference is givento starch degradation products which have not undergone chemicalmodification.

One particularly preferred embodiment of the present invention usesstarch degradation products, with or without chemical modification,which have a weight-average molecular weight, M_(w) in the range from500 to 500000 daltons, in particular from 1000 to 30000 daltons and verypreferably from 3000 to 10000 daltons. Starches of this kind are fullysoluble in water at 25° C. and 1 bar, the solubility limit generallybeing above 50% by weight, which is particularly favorable for thepreparation of the aqueous polymer dispersions of the invention. Figuresfor the molecular weight of the saccharified starches for use inaccordance with the invention are based on determinations made by meansof gel permeation chromatography under the following conditions:

Columns: 3 steel columns, 7.5×600 mm, packed with TSK-Gel G 2000 PW andG 4000 PW. Pore size 5 mm.

Eluent: Distilled water

Temp.: RT (room temperature)

Detection: Differential refractometer (e.g. ERC 7511)

Flow rate: 0.8 ml/min. pump: (e.g. ERC 64.00)

Injector: 20 ml valve: (e.g. VICI 6-way valve)

Evaluation: Bruker Chromstar GPC software

Calibration: In the low molecular mass range, using glucose, raffinose,maltose, and maltopentose. For the higher molecular mass range, usingpullulan standards with a polydispersity <1.2.

The non cyclic polysaccharides are generally present entirely in onlyone of the possible enantiomeric forms.

The monomers to be polymerized suitably include any desired monomers.

Preference is given to free-radically polymerizable monomers,particularly those having a polymerizable double bond.

At least 10%, preferably at least 50%, or preferably at least 80%, andvery preferably 100% by weight of the total monomers used to prepare thepolymer ought to be prochiral.

The monomers, accordingly, cannot exclusively comprise, say, ethylene,which is not prochiral.

Preferably at least some of the monomers used are monomers having awater solubility of less than 20 g of monomer per liter of water (20°C., 1 bar).

Preferably at least 50% by weight, in particular at least 80% by weight,and very preferably at least 95% by weight of the monomers are monomerswith the above limited water solubility.

These monomers (monomers a for short) include ethylenically unsaturatedmonomers which are insoluble in water or have a solubility in water at20° C. of not more than 20 g/l. Examples of such compounds are C₂ to C₄₀alkyl esters of acrylic acid or C, to C₄₀ alkyl ester of methacrylicacid, such as methyl methacrylate, ethyl acrylate, ethyl methacrylate,propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropylmethacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate,isobutyl methacrylate, tert.-butyl acrylate, pentyl acrylate, pentylmethacrylate, n-hexyl acrylate, n-hexyl methacrylate, n-heptyl acrylate,n-heptyl methacrylate, n-octyl acrylate, n-octyl methacrylate,2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, decyl acrylate, decylmethacrylate, lauryl acrylate, lauryl methacrylate, palmityl acrylate,palmityl methacrylate, octadecyl acrylate, octadecyl methacrylate,phenoxyethyl acrylate, phenoxyethyl methacrylate, and phenylacrylate andphenyl methacrylate.

Further monomers of group (a) are α-olefins having 2 to 30 carbon atomsand also polyisobutylenes, having 3 to 50, preferably 15 to 35,isobutene units. Examples of α-olefins are ethylene, propylene,n-butene, isobutene, pent-1-ene, cyclopentene, hex-1-ene, cyclohexene,oct-1-ene, diisobutylene (2,4,4-trimethyl-1-pentene alone or in amixture with 2,4,4-trimethyl-2-pentene), dec-1-ene, dodec-1-ene,octadec-1-ene, C₁₂/C₁₄ olefins, C₂₀/C₂₄ olefins, styrene,α-methylstyrene, polypropylenes having a terminal vinyl or vinylidengroup and from 3 to 100 propylene units, oligohexene or oligooctadecene.

A further class of monomers of group (a) are N-alkyl-substitutedacrylamides and methacrylamides, such as N-tert-butylacrylamide,N-hexylmethacrylamide, N-octylacrylamide, N-nonylmethacrylamide,N-dodecylmethacrylamide, N-hexadecylmethacrylamide,N-methacrylamidocaproic acid, N-methacrylamidoundecanoic acid,N,N-dibutylacrylamide, N-hydroxyethylacrylamide andN-hydroxyethylmethacrylamide.

Other group (a) monomers are vinyl alkyl ethers having 1 to 40 carbonatoms in the alkyl radical, examples being methyl vinyl ether, ethylvinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinylether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, decyl vinylether, dodecyl vinyl ether, octadecyl vinyl ether, 2-(diethylamino)ethylvinyl ether, 2-(di-n-butyl-amino)ethyl vinyl ether, methyldiglycol vinylether and the corresponding allyl ethers such as allyl methyl ether,allyl ethyl ether, allyl-n-propyl ether, allyl-isobutyl ether, andallyl-2-ethylhexyl ether. Moreover, suitability as compounds of group(b) is possessed by the esters of maleic acid and fumaric acid which areinsoluble in water or have a solubility of in water of up to 20 g/l atmost and which derive from monohydric alcohols having 1 to 22 carbonatoms, examples for these esters being mono-n-butyl maleate, dibutylmaleate, monodecyl maleate, didodecyl maleate, monooctadecyl maleate,and dioctadecyl maleate. Also suitable are vinyl esters of saturated C₃to C₄₀ carboxylic acids such as vinyl propionate, vinyl butyrate, vinylvalerate, vinyl 2-ethylhexanoate, vinyl decanoate, vinyl palmitate,vinyl stearate, and vinyl laurate. Other group (b) monomers aremethacrylonitrile, vinyl chloride, vinylidene chloride, isoprene, andbutadiene.

The abovementioned monomers of group (a) can be used alone or in amixture. Compounds of preferred suitability as monomers (a) are C₂ toC₃₀ alkyl ester of acrylic acid, C₁ to C₃₀ alkyl ester of methacrylicacid, C₂ to C₃₀ a-olefins, C₁ to C₂₀ alkyl vinyl ethers, styrene,butadiene, isoprene or mixtures thereof. Particularly preferred monomers(a) are methyl methacrylate, butyl acrylate, lauryl acrylate, stearylacrylate, isobutene, hex-1-ene, diisobutene, dodec-1-ene, octadec-1-ene,polyisobutene having 15 to 35 isobutene units, styrene, methyl vinylether, ethyl vinyl ether, octadecyl vinyl ether or mixtures thereof.

Further suitable monomers (a) include monomers having a crosslinkingaction, which contain at least two ethylenically unsaturated,nonconjugated double bonds in the molecule. Compounds of this kind aregenerally used in a relatively small amount together with water-solublemonomers, in order to prepare water-swellable polymers. Such copolymersare important, for example, as water-absorbing polymers. The problemhere is that for this purpose it is generally been necessary to usewater-soluble crosslinkers in order to prepare uniform polymers. Inaccordance with the process of the invention it is possible tocopolymerize even very sparingly water-soluble or water-insolublecrosslinkers homogeneously into the resultant crosslinked copolymer witha predominant fraction of water-soluble monomers. Examples of suitablecrosslinkers of component (b) are divinylbenzene, diallylphthalate,allyl vinyl ether and/or diallylfumarate. The water-insolublecrosslinkers can be polymerized alone, to form homopolymers, or togetherwith water-soluble monomers, to form copolymers. If crosslinkers areused in the copolymerization of water-soluble monomers the amount ofcrosslinker, based on the amount of monomers used in the polymerization,is from 0.05 to 10%, preferably from 0.1 to 2% by weight.

Complexes of the monomers in the optically active complexing agent canbe prepared by known methods. For example, a cyclodextrin and/or acompound which comprises cyclodextrin structures, and at least onemonomer (a), can be dissolved together in a solvent and the solution canbe heated where appropriate. Removal of the solvent leaves acrystallining complex. One molecule of the complexing agent is able tocomprise in bound form up to two molecules of the monomers (a) incomplex form. These complexes are referred to in the literature ashost/guest complexes. The cyclodextrins or compounds which comprisecyclodextrin structures comprise the water-insoluble monomer in theircavities.

The complexes can also be prepared, for example, by introducing theindividual components into a solvent which dissolves, for example, onlythe cyclodextrins and/or compounds which comprise cyclodextrinstructures, but not the water-insoluble monomers. The process ofhost/guest complex formation can be accelerated by heating, stirring,ultrasound treatment or other mechanical or thermal measures. It is alsopossible to form the complexes in a solvent which dissolves only themonomers (a) but not the cyclodexrins. The complexes can also be formedin the absence of solvent and diluent, if the cyclodextrins and/orcompounds which comprise cyclodextrin structures are present insufficiently fine distribution and are contacted with the monomers (a).A further possibility is to evaporate the monomers (a) and cause them toact on the cyclodextrins from the gas phase. A procedure of this kind isparticularly preferred, for example, when preparing complexes ofcyclodextrins and low-boiling monomers (b). For example, ethylene,propylene or isobutene can be passed over finely divided cyclodextrins.The formation of the complexes can be performed under atmosphericpressure or under subatmospheric or superatmospheric pressure. The molarratio of the components (a):(b) is from 1:2 to 10:1 and is preferablysituated within the range from 1:1 to 5:1.

The monomers (a) can be free-radically polymerized alone or in a mixturewith one another. Another possibility is to copolymerize monomers (a)with water-soluble monomers. Suitable water-soluble monomers, which willbe referred to below as monomers of group (b), are, for example,monoethylenically unsaturated C₃ to C₅ carboxylic acids, their amidesand esters with amino alcohols of the formula

where R=C₂ to C₅ alkylene, R¹, R², and R³=H, CH₃, C₂H₅, C₃H₇ and X^(⊖)is an anion. Suitability is likewise possessed by amides derived fromamines of the formula

The substituents in formula II and X^(⊖) have the same definition as informula I.

These compounds comprise, for example, acrylic acid, methacrylic acid,crotonic acid, itaconic acid, maleic acid, fumaric acid, acrylamide,methacrylamide, crotonamide, dimethylaminoethyl acrylate,diethylaminoethyl acrylate, dimethylaminoneopentyl acrylate anddimethylaminoethyl methacrylate, dimethylaminopropyl acrylate,dimethylaminoneopentyl acrylate and dimethylaminoneopentyl methacrylate.The basic acrylates and methacrylates and/or basic amides deriving fromthe compounds of the formula II are used in the form of the salts withstrong mineral acids, sulfonic acids or carboxylic acids or inquaternized form. The anion X^(⊖) for the compounds of the formula I isthe acid residue of the mineral acids or of the carboxylic acids ormethosulfate, ethosulfate or halide from a quaternizing agent.

Further water-soluble monomers of group (b) are N-vinylpyrrolidone,N-vinylformamide, acrylamidopropansulfonic acid, vinylphosphonic acidand/or alkali metal salts and/or ammonium salts of vinylsulfonic acid.For the polymerization the other acids can likewise be used either innon-neutralized form or in partially neutralized form or with up to 100%neutralization. Suitable water-soluble monomers of group (c) alsoinclude diallylammonium compounds, such as dimethyldiallylammoniumchloride, diethyldiallylammonium chloride or diallylpiperidiniumbromide, N-vinylimidazolium compounds, such as salts or quaternarizationproducts of N-vinylimidazole and 1-vinyl-2-methylimidazole, andN-vinylimidazoline, such as N-vinylimidazoline,1-vinyl-2-methylimidazoline, 1-vinyl-2-ethylimidazoline or1-vinyl-2-n-propylimidazoline, which are likewise used in quaternarizedform or as a salt in the polymerization.

Preferred group (b) monomers are monoethylenically unsaturated C₃ to C₅carboxylic acids, vinylsulfonic acid, acrylamidomethylpropanesulfonicacid, vinylphosphonic acid, N-vinylformamide, dimethylaminoethyl(meth)acrylates, alkali metal salts or ammonium salts of theabovementioned monomers comprising acid groups, or mixtures of themonomers with one another. Of particular economic importance is the useof acrylic acid or mixtures of acrylic acid and maleic acid or theiralkali metal salts in the preparation of hydrophobically modifiedwater-soluble copolymers.

The polymerization of the water-insoluble monomers and, whereappropriate, of the water-soluble monomers takes places preferably inthe manner of a solution or precipitation polymerization, preferably inwater, water-miscible liquids or mixtures thereof, more preferably inwater or in aqueous medium. In the present context an aqueous mediummeans mixtures of water and water-miscible organic liquids. Examples ofwater-miscible organic liquids are glycols such as ethylene glycol,propylene glycol, block copolymers of ethylene oxide and propyleneoxide, alkoxylated C₁ to C₂₀ alcohols, acetates of glycols andpolyglycols, alcohols such as methanol, ethanol isopropanol, andbutanol, acetone, tetrahydrofuran, dimethylformamide,N-methylpyrrolidone or else mixtures of said solvents. Where thepolymerization takes place in mixtures of water and water-misciblesolvents the fraction of water-miscible solvents in the mixture is up to45% by weight. With preference, however, the polymerization is conductedin water.

The polymerization of the monomers takes place in accordance with theinvention at temperatures below 20° C., more preferably below 15° C.,and very preferably below 10° C., and in particular below 0° C. Attemperatures below 10° C. or below 0° C. it is possible whereappropriate to use auxiliaries which lower the freezing point of thesolvent or solvent mixtures used.

The polymerization can be conducted batchwise or continuously.Preferably at least a fraction of the monomers, initiators, and, whereused, regulators is metered into the reaction vessel at a uniform rateduring the polymerization. In the case of relatively small batches,however, it is also possible to charge the monomers and thepolymerization initiator to the reactor and polymerize them, in whichcase it may be necessary to ensure sufficiently rapid removal of theheat of polymerization by cooling.

Suitable polymerization initiators are the compounds commonly used forfree-radical polymerizations, which yield free radicals under thepolymerization conditions, examples being peroxides, hydroperoxides,peroxodisulfates, percarbonates, peroxy esters, hydrogen peroxide, andazo compounds. Examples of initiators are hydrogen peroxide, dibenzoylperoxide, dicyclohexyl peroxide dicarbonate, dilauryl peroxide, methylethyl ketone peroxide, acetylacetone peroxide, tert-butyl hydroperoxide,cumene hydroperoxide, tert-butyl perneodecanoate, tert-amyl perpivalate,tert-butyl perpivalate, tert-butyl perneohexanoate, tert-butylper-2-ethylhexanoate, tert-butyl perbenzoate, and lithium, sodium,potassium, and ammonium peroxodisulfates, azoisobutyronitrile,2,2′-azobis(2-amidinopropane) dihydrochloride,2-(carbamoylazo)-isobutyronitrile, and 4,4′-azobis(4-cyanovaleric acid).The initiators are used usually in amounts of up to 15%, preferably from0.02 to 10%, by weight, based on the monomers to be polymerized.

The initiators can be used alone or in a mixture with one another. Alsosuitable is the use of the known redox catalysts in which the molaramount of the reducing component used is substoichiometric. Examples ofknown redox catalysts include salts of transition metals, such asiron(II) sulfate, cobalt(II) chloride, nickel(II) sulfate, copper(I)chloride, manganese(II) acetate, and vanadium(III) acetate. Furthersuitable redox catalysts include sulfur compounds which have a reducingaction, such as sulfites, bisulfites, thiosulfates, dithionites andtetrathionates of alkali metals and ammonium compounds, or phosphoruscompounds which have a reducing action and in which phosphorus has anoxidation number of from 1 to 4, such as sodium hypophosphite,phosphorous acid, and phosphites, for example.

In order to control the molecular weight of the polymers it is possiblewhere appropriate to conduct the polymerization in the presence ofregulators. Examples of suitable regulators include aldehydes such asformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde andisobutyraldehyde, formic acid, ammonium formiate, hydroxylammoniumsulfate, and hydroxylammonium phosphate. It is also possible to useregulators comprising sulfur in organically bonded form, such as organiccompounds containing SH groups, such as thioglycolacetic acid,mercaptopropionic acid, mercaptoethanol, mercaptopropanol,mercaptobutanols, mercaptohexanol, dodecyl mercaptan, and tert-dodecylmercaptan. Further regulators which can be used include salts ofhydrazine, such as hydrazinium sulfate. The amounts of regulator, basedon the monomers to be polymerized, are from 0 to 20%, preferably from0.5 to 15% by weight.

Where, for the polymerization, the monomers (b) are introduced into thereactor not in the form of complexes of complexing agent and group (b)monomers, the monomers (b) can be metered into an aqueous solution ofthe complexing agent and subjected to polymerization in the presence ofpolymerization initiators and, where used, regulators. Within thereaction medium, complexes are formed from the monomers (b) and thecomplexing agents present therein.

Following the polymerization the polymers are usually separate from thecomplexing agents. For example, copolymers of acrylic acid containingmore than 20% by weight of water-insoluble monoethylenically unsaturatedcompounds such as stearyl acrylate or polyisobutene are precipitatedfrom the aqueous reaction solution. Where the polymers followingpreparation are still in the form of inclusion compounds, they can beliberated from the inclusion compounds and isolated by means, forexample, of adding wetting agents, for example, such as ethoxylatedlong-chain alcohols to the reaction mixture.

According to the process of the invention it is possible to obtain bothlow and high molecular mass polymers.

The process is suitable for preparing polymers having a weight-averagemolecular weight M_(w) of from 5000 to 500000 g/mol. The process is alsosuitable for preparing polymers having a molecular weight M_(w) of morethan 1 million g/mol, and in particular more than 1.5 million.

M_(w) is generally less than 10 million and is determined by gelpermeation chromatography.

The polymer comprises ordered regions (isotactic and/or syndiotacticfractions) alongside unordered regions (atactic regions). The regionsdiffer in their phase transition temperatures. In differential thermalanalysis or in dielectric spectroscopy, therefore, at least two phasetransition temperatures are found. These can be, for example, two glasstransition temperatures (glass state/liquid transition) or at least oneglass transition temperature and one melting point (crystalline/liquidtransition).

The weight fraction of the ordered regions in the polymer as a whole ispreferably at least 0.1% by weight, in particular at least 0.5% byweight, more preferably at least 2% by weight or 5% by weight or atleast 10% by weight.

Besides the ordered regions the polymer comprises other, i.e., unorderedregions. The fraction of the ordered regions is generally less than 90%by weight, in particular less than 75% by weight, and more preferablymore than 70% by weight.

In one particularly preferred embodiment the fraction of the orderedregions is from 20 to 70% by weight, in particular from 30 to 70% byweight.

The tacticity can be determined by means of ¹H NMR spectroscopy(integral of the methylene signals).

It is assumed that the very existence of ordered regions alongsideunordered regions produces particular elasticity in the resultantpolymers.

On account of their elasticity the polymers are suitable as coatingcompositions. They are particularly suitable for use as paints orcoatings on leather, with polymers particularly suitable for thisutility having an M_(w) of more than 1 million g/mol.

The coating compositions, or paints, leather coatings, can consistsolely of the polymer as binder; naturally, however, they may alsocomprise additives such as dyes, pigments, leveling agents, thickeners,etc.

The polymers are also suitable for use as detergent additives, as scaleinhibitors or as dispersants. For these applications the polymerpreferably has a weight-average molecular weight of from 5000 to 500000.Scale inhibitors are additives which reduce the formation of deposits inhot water, such as in evaporators, for example.

EXAMPLES

Low-temperature polymerization of cyclodextrin-complexed vinyl monomersin aqueous phase

1 Monomers

FIG. 1 depicts the monomers used. The monomers were purified by vacuumdistillation prior to the polymerization experiments.

FIG. 1: Methyl methacrylate (1), phenyl methacrylate (2), t-butylmethacrylate (3), cyclohexyl acrylate (4), styrene (5).2 Polymerization Experiments2.1 Homopolymerization

The technical-grade cyclodextrin (CD) used comes from Wacker Chemie GmbH(Cavasol W7M Pharma) and has a degree of methylation of 1.8 per glucoseunit.

The reaction medium used was demineralized water.

¹J. A. Shetter, Polymer Letters, 1963,1,209-213.

²C. Pilcher, W. T. Ford, Journal of Polymer Science: Part A: Polym.Chem., 2001, 39, 519.

³R. J. Andrews, E. A. Grulke, in Polymer Handbook, 4th ed., J. Brandrup,E. H. Immergut, E. A. Grulke, Eds.; Wiley: New York, 1999; p V1/204.

⁴E. H. Immergut, J. Brandrup, Polymer Handbook, 1989, John Wiley & Sons,New York.

2.1.1 Homopolymerization of Methyl Methacrylate (1)

FIG. 2: Homopolymerization of methyl methacrylate in the presence of CD.

6.66 g of CD (5 mmol) are weighed out into a 50 ml single-necked flaskwith septum and are dissolved in 10 ml of distilled water. Following theaddition of 0.711 g (5 mmol) of methyl methacrylate the reactionsolution is flushed with nitrogen for 30 minutes while stirring.Formation of the complex is evident from the clarification of thesolution, which to start with is turbid as a result of dispersed monomerdroplets. Following the addition of 1 g of NaCl the reaction solution iscooled in an ice bath to the reaction temperature. Subsequently thepolymerization is initiated by adding 10 mol % Na₂S₂O₅ and K₂S₂O₈. Aftera reaction time of 2 h the precipitated polymer is filtered off, washedwith water and ethanol and dried under reduced pressure. Table 1 liststhe reaction temperatures, T, of the polymerizations carried out andalso the tacticity of the polymers prepared and their T_(g) values. Thetacticity of the polymer samples was ascertained from the integrals ofthe methylene signals in the ¹H NMR spectrum (Bruker Avance DRX500 (500MHz)). TABLE 1 Polymerization of methyl methacrylate (1). Reactiontemperature Tacticity/% T/° C. isotactic atactic syndiotactic Tg/° C.−7° C. 5.9 36.2 57.9 98 0° C. 5.5 38.0 56.5 116 RT 5.6 38.5 55.9 120 0°C. a) 3.7 33.3 63.0 121a) Polymerization of methyl methacrylate in H₂O withot CD underidentical experimental conditions.

The literature values of the glass transition temperature of polymethylmethacrylate amount to 115° C. for a predominantly syndiotactic sampleand 45° C. for a predominantly isotactic sample.⁵ According to resultsto date, a lowering of the polymerization temperature T leads to anincrease in the isotactic fraction, as suggested both by the evaluationof the ¹H NMR spectra and by the lowering of the T_(g) value.⁵ J. A. Shetter, Polymer Letters, 1963, 1, 209-213.2.1.2 Homopolymerization of Phenol Methacrylate (2)

FIG. 3: Homopolymerization of phenyl methacrylate in the presence of CD.Experiments A

Phenyl methacrylate is homopolymerized in water or in an ethanol/watersolution in the form of a cyclodextrin complex (monomer:CD (1:1.25))under different reaction conditions (temperature, reacton time) usingthe redox initiator system K₂S₂O₈/Na₂S₂O₅ under an N₂ atmosphere. Thethermal properties of the resulting polymers are investigated by meansof DSC (T_(g), T_(m)). The reaction conditions of the experimentscarried out and also the corresponding T_(g) values are listed inTable 1. TABLE 2 Polymerization of phenyl methacrylate (2). T/° C. t/hInt./mol % m(NaCl)/g Solv./ml Tg/° C. rt 3 5 — 10 ml H₂O 103.83 0 3 5 —10 ml H₂O 117.20 −5 3 5 —  8 ml H₂O 121.39  2 ml EtOH −10 3 5 —  2 mlH₂O 124.43  8 ml EtOH rt 1 2.5 1 10 ml H₂O 126.27 0 1 2.5 1 10 ml H₂O126.21 −5 1 2.5 1 10 ml H₂O 122.84Experiments B

Phenyl methacrylate (5 mmol, 0.8 ml) is homopolymerized in the form of acyclodextrin complex (monomer:CD (1:1.25)) in 10 ml of water at 60° C.,25° C., 0° C., −10° C. and −20° C. with 5 mol % of a redox initiatorsystem K₂S₂O₈/Na₂S₂O₅ under an N₂ atmosphere. The reaction time for allbatches is 2 h. In the case of the reaction temperatures 25° C., 0° C.and −10° C., 5 g of MgCl₂.6H₂O are added to the aqueous complexsolution. At the reaction temperature of −20° C., 5 g of CaCl₂.6H₂O areadded to the aqueous complex solution in order to prevent the formationof ice crystals. The polymerization is initiated by addition of theredox initiator system K₂S₂O₈/Na₂S₂O₅ and is stopped after 2 h by adilution of the solution with a 1:1 methanol/H₂O solution and immediateremoval of the precipitated polymer by filtration. The polymer is washedwith methanol and H₂O. Subsequently the polymer is dissolved in tolueneand the filtered toluene solution is added to vigorously stirredmethanol in order to reprecipitate the polymer. The reaction conditionsof the experiments carried out and also the corresponding T_(g) valuesare listed in Table 3. TABLE 3 Polymerization of phenyl methacrylate(2). T/° C. t/h Int./mol % m(salt)/g Tg(average)/° C. Tg(onset)/° C. 602 5 — 126.89 119.91 25 2 5 5 g MgCl₂ 128.21 122.21 0 2 5 5 g MgCl₂128.01 122.95 −10 2 5 5 g MgCl₂ 128.76 122.34Values found in the literature for the glass transition temperature ofpolyphenyl methacrylate are between 122-128° C., as determined by DSCmeasurements using the average-value method⁶, or values as low as 110°C. and as high as 134° C., as determined by other methods⁷.⁶SC. Pilcher, W. T. Ford, Journal of Polymer Science: Part A: Polym.Chem., 2001, 39, 519.⁷ R. J. Andrews, E. A. Grulke, in Polymer Handbook, 4th ed., J.Brandrup, E. H. Immergut, E. A. Grulke, Eds.; Wiley: New York, 1999; pV1/204.2.1.3 Homopolymerization of t-butyl methacrylate (5).

FIG. 4: Homopolymerization of t-butyl methacrylate in the presence ofCD.

t-Butyl methacrylate (5 mmol, 0.81 ml) is homopolymerized in the form ofa cyclodextrin complex (monomer:CD (1:1.25)) in 10 ml of water at 60°C., 25° C., 0° C., −10° C. and −20° C. with 5 mol % of a redox initiatorsystem K₂S₂O₈/Na₂S₂O₅ under an N₂ atmosphere. The reaction time for allbatches is 2 h. At reaction temperatures of 25° C., 0° C., −10° C. and−20° C., 5 g of CaCl₂.6H₂O are added to the aqueous complex solution inorder to prevent the formation of ice crystals. The polymerization isinitiated by addition of the redox initiator system and is terminatedafter 2 h by a dilution of the solution with a 1:1 methanol/H₂O solutionand immediate removal of the precipitated polymer by filtration.

The reaction conditions of the experiments carried out and also thecorresponding T_(g) values are listed in Table 4. TABLE 4 Polymerizationof poly(t-butyl methacrylate). Int./ Tg(average)/ Tg(onset)/ T/° C. t/hmol % m(CaCl₂*6H₂O) ° C. ° C. 60 2 5 — 59.94 44.07 25 2 5 5 56.62 a)43.20 a) 0 2 5 5 51.85 41.37 −10 2 5 5 76.83 57.44a) T_(g) value from 3rd heating curve

The literature values of atactic, syndiotactic and isotacticpoly(t-butyl methacrylate) are set out in Table 5. TABLE 5 Literaturevalues for the glass transition temperature, T_(g), of poly(t-butylmethacrylate). Poly(t-butyl methacrylate) Tg/° C. Atactic 117.85Syndiotactic 113.85 Isotactic 6.852.1.4 Homopolymerization of Cyclohexyl Acrylate (4)

FIG. 5: Homopolymerization of cyclohexyl acrylate in the presence of CD.Experiments A

8.2 g (6.25 mmol) of CD are weighed out into a 100 ml single-neckedflask with septum and are dissolved in 10 ml of distilled water.Subsequently 0.711 g (5 mmol) of cyclohexyl acrylate is added to thesolution. The formation of a complex is from the clearing of thesolution, which to start with is turbid as a result of dispersed monomerdroplets. Following the addition of 1 g of NaCl the solution is flushedwith nitrogen while stirring and is cooled in an ice bath to thereaction temperature. Thereafter the polymerization is initiated byaddition of 2.5 mol % of K₂S₂O₈ and Na₂S₂O₅. After a reaction time of 1h the precipitated polymer is filtered off and washed with water andmethanol. The reaction conditions of the experiments carried out andalso the corresponding T_(g) values are listed in Table 6. TABLE 6Polymerization of cylohexyl acrylate (3). T/° C. t/h Int./mol %m(NaCl)/g Tg CHA1 rt 1 2.5 1 34.97 CHA2 −5 2 2.5 1 29.42Experiments B

Cyclohexyl acrylate (5 mmol, 0.9 ml) is homopolymerized in the form of acyclodextrin complex (monomer:CD (1:1.25)) in 10 ml of water at 60° C.,25° C., 0° C. and −10° C. with 5 mol % of the redox initiator systemK₂S₂O₈/Na₂S₂O₅ under an N₂ atmosphere. The reaction time for all batchesis 2 h. At reaction temperatures of 25° C., 0° C. and −10° C., 5 mg ofMgCl₂.6H₂O are added to the aqueous complex solution in order to preventthe formation of ice crystals. The polymerization is initiated byaddition of the redox initiator system K₂S₂O₈/Na₂S₂O₅ and is terminatedafter 2 h by dilution with the reaction solution with a 1:1 methanol/H₂Osolution, addition of 4-tert-butylpyrocatechol and immediate removal ofthe precipitated polymer by filtration.

The reaction conditions of the experiments carried out and also thecorresponding T_(g) values are listed in Table 7. TABLE 7 Polymerizationof cyclohexyl acrylate (4). Int./ Tg(average)/ Tg(onset)/ T/° C. t/h mol% m(MgCl₂*6 H₂O) ° C. ° C. 60 2 5 — 30.04 20.81 25 2 5 5 23.99 8.15 0 25 5 32.02 25.38 −10 2 5 5 23.93 17.07

The T_(g) value of poly(cyclohexyl acrylate) is affected by thetacticity of the polymer, as is apparent from Table 8. Conversely,investigating the T_(g) value promises to reveal information on thetacticity of the polymer.

Table 8: Literature values for the glass transition temperature, T_(g),of poly(cyclohexyl acrylate).⁸⁸ E. H. Immergut, J. Brandrup, Polymer Handbook, 1989, John Wiley &Sons, New York.Poly(cyclohexyl acrylate) Tg/° C. Conventional 18.85 Syndiotactic 15.85isotactic 11.852.1.5 Homopolymerization of Styrene (5)

FIG. 5: Homopolymerization of styrene in the presence of CD.Experiments A

Styrene is homopolymerized in water in the form of a cyclodextrincomplex (monomer:CD (1:1.25)) under different reaction conditions(reaction temperature, reaction time and initiator quantity) with theredox initiator system K₂S₂O₈₁Na₂S₂O₅ under an N₂ atmosphere. Thethermal properties of the resulting polymers are investigated by meansof DSC (T_(g), T_(m)). The reaction conditions of the experimentscarried out and also the corresponding T_(g) values are listed inTable 1. TABLE 9 Polymerization of styrene T/° C. t/h Init./mol % Tg/°C. S1 rt 2 2.5 104.54 S2 0 3 2.5 105.93 S3 −5 3 5 98.91 HC1a rt 2 597.00Experiments B

Styrene (5 mmol, 0.6 ml) is homopolymerized in the form of acyclodextrin complex (monomer:CD (1:1.25)) in 10 ml of water at 60° C.,25° C., 0° C., −10° C. and −20° C. with 5 mol % of the redox initiatorsystem K₂S₂O₈/Na₂S₂O₅ under an N₂ atmosphere. The reaction time for allbatches is 2 h. At reaction temperatures of 25° C., 0° C. and −10° C., 5g of MgCl₂.6H₂O are added to the aqueous complex solution in order toprevent the formation of ice crystals. The polymerization is initiatedby addition of the redox initiator system and is terminated after 2 h bydilution of the reaction solution with a 1:1 methanol/H₂O solution,addition of 4-tert-butylpyrocatechol and immediate removal of theprecipitated polymer by filtration. The polymer is washed with H₂O andmethanol and then dissolved in THF and reprecipitated by addition of thepolymer solution to vigorously stirred methanol.

The syndiotactic reference polymer provided by BASF possesses a T_(g)value of 97.18° C. and a melting peak at 270.51° C. TABLE 10Polymerization of styrene Int./ Tg(average)/ Tg(onset)/ T/° C. t/h mol %m(MgCl₂*6 H₂O) ° C. ° C. 60 2 5 — 94.39 88.74 25 2 5 5 103.01 99.46 0 25 5 106.84 102.50 −5 2 5 5 94.81 88.16 −10 2 5 5 91.78 65.06

In the literature it is stated both that for syndiotactic and isotacticpolystyrene the glass transition temperature for the amorphous phase is100° C.⁹, and that the glass transition Temperature of syndiotacticpolystyrene has a value of 104° C.¹⁰. The melting point of syndiotacticpolystryene, at 273° C., however, is much higher than the melting pointof isotactic polystryene (176-224° C.).¹¹⁹A. J. Pasztor, Jr., B. G. Landes, P. J. Karjala, Thermochim. Acta,1991, 177, 187.¹⁰M. Malanga, Adv. Mater., 2000, 12, 1869.¹¹A. J. Pasztor, Jr., B. G. Landes, P. J. Karjala, Thermochim. Acta,1991, 177, 187.

3 Differential Scanning Calorimetry (DSC)

The DSC spectra were recorded with a Mettler DSC 30 instrument using5-10 mg of polymer.

The sample of polymethyl methacrylate was heated from −50° C. to 200° C.at 5° C. per minute. The sample is held at 200° C. for 10 minutes andthen cooled to −40° C. (−10° C./min). Subsequently the sample is heatedagain to 200° C. (5° C./min).

The polymer samples of polyphenyl methacrylate, polycyclohexyl acrylateand styrene from Experiments A were heated to 200° C. at 10° C. perminute and then cooled to −50° C. (−5° C./min), a temperature which washeld for 10 minutes. The sample is then heated again to 200° C. (5°C./min), thereafter cooled to −50° C. (−5° C./min) and brought again to200° C. (5° C./min). The T_(g) values were evaluated using—unlessindicated otherwise—the average of the second heating phase.

The polymer samples of polyphenyl methacrylate, poly(t-butylmethacrylate), polycyclohexyl acrylate and styrene from Experiments Bwere heated to 200° C. at 15° C. per minute and then cooled to −50° C.(−15° C./min), a temperature which was held for 10 minutes. The sampleis then heated again to 200° C. (15° C./min), thereafter cooled to −50°C. (−15° C./min) and brought again to 200° C. (15° C./min).

The T_(g) values were evaluated using—unless indicated otherwise—theaverage of the second heating phase.

¹²M. Malanga, Adv. Mater., 2000, 12, 1869.

1. A process for preparing a polymer having isotactic or syndiotacticregions (ordered regions for short) by polymerizing polymerizablecompounds (monomers) in the presence of an optically active compound ascomplexing agent, wherein more than 50% by weight of the opticallyactive compound is in the form of only one of the possible enantiomers,the polymerization takes place at temperatures below 20° C., and atleast 10% by weight of the monomers are prochiral compounds.
 2. Theprocess as claimed in claim 1, wherein the complexing agent surroundsthe monomers in the complex.
 3. The process as claimed in claim 1,wherein the entire complexing agent is in the form of just one of thepossible enantiomers.
 4. The process as claimed in claim 1, wherein thecomplexing agent is cyclodextrin or a non cyclic polysaccharide.
 5. Theprocess as claimed in claim 1, wherein at least 50% by weight of themonomers to be polymerized are monomers having a solubility of less than20 g of monomer per liter of water.
 6. The process as claimed in claim1, wherein the polymerization takes place in water, water-misciblesolvents or mixtures thereof.
 7. The process as claimed in claim 1,wherein the polymerization takes place at temperatures below 0° C., inthe presence or absence of auxiliaries which lower the freezing point ofthe solvent or solvent mixture used.
 8. The process as claimed in claim1, wherein the weight-average molecular weight, Mw, of the polymersobtained is from 5000 to 500000 g/mol, measured by gel permeationchromatography.
 9. The process as claimed in claim 1, wherein theweight-average molecular weight, Mw, of the polymers obtained is atleast 1 million, measured by gel permeation chromatography.
 10. Theprocess as claimed in claim 1, wherein the polymer in differentialthermal analysis has at least two glass transition temperatures(frozen-in glass state/liquid transition) or at least one glasstransition temperature and one melting point (crystalline/liquidtransition).
 11. The process as claimed in claim 1, wherein the fractionof the ordered regions amounts to from 0.1 to 90% by weight of the totalpolymer.
 12. A polymer obtained by a process as claimed in claim 1.13-14. (canceled)
 15. A paint or a leather coating comprising thepolymer as claimed in claim
 12. 16. A method for producing a paint or aleather coating comprising adding the polymer as claimed in claim 13 toa paint or a leather coating formulation.
 17. A detergent additivecomprising the polymer as claimed in claim
 12. 18. A scale inhibitorcomprising the polymer as claimed in claim
 12. 19. A dispersantcomprising the polymer as claimed in claim
 12. 20. A method forproducing a detergent comprising adding the detergent additive asclaimed in claim 17 to a detergent formulation.
 21. A method forproducing a scale polymer inhibitor comprising adding the polymer asclaimed in claim 12 to a scale inhibitor formulation.
 22. A method forproducing a dispersant comprising adding the polymer as claimed in claim12 to a dispersant formulation.